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Oil Field Engines & Related EquipmentOFES members otherwise known as "Oafs". If you like "BIG OLD GREASY RUSTY OIL FIELD ENGINES, you're in the right place. Founded by Russell Farmer.

There may be a cam available on the shaft already. See if it has a 2-bolt blank cover or the valve body located on top of the cam box at the flywheel end where Bill's mag is. This is where the air start timing cam is located on many of these engines, and it may work just fine for an OC. With an OC, you won't need no stinkin' air start. You would need to find or fabricate a bracket to hold the mag rigidly in place. A scrap of 1" plate with a slot milled in it for the mag pushrod might work just fine. A couple of "ears" drilled to match the air start valve or block off plate would allow it to mount to the existing holes. You might have to make an extended roller actuator out of a piece of keystock, but I think you could use one from a 4 cycle Superior and just put a keystock spacer in the slot in the back of the mag if needed.

Correction: On the 1960s DP 115 Ajax engines, there are 2 covers or valve bodies on the cam box. On these engines, the cover/valve nearest the flywheel end is for the gas injection timing valve, if the engine is so equipped. The 2 engines I have don't have gas injection and have a cover plate here. The next cover or valve body going toward the head on these engines is for the air start timing valve. Both these engines have working air start with the valves in place. I suspect that on these older Ajax engines, the gas injection (flywheel end) cam would work fine for operating an OC mag since the cam high point is up when the engine is close to TDC and the cam stroke is about right. The old Superior engine has one cover at the flywheel end of the cam box that I believe (after seeing Bill's engine picture) will work for either air start or an OC type mag. This engine has a rotary mag that sticks out to the side like Doug described and an arm coming out of the cam box to operate the lubricator. The newer engines have a rotary drive lubricator running off the head end of the cam box mounted where the old engines have the water pump.

Went out and took a picture of the AJAX, removed the mag to see what the cam looked like. There wasn't much to see. The Wico cam, as AJAX calls it, is more like an eccentric. I would guess about 90 degrees of duration maybe 3/8" lift. The centerline is retarded to so that the mag will fire about 60 degrees from TDC when rotating the engine in reverse, and the mag will also fire about 30 degrees BTC when rotating in proper direction. About 60 degrees from TDC is about all one can manage rotating the flywheel in reverse because of compression One still might be able to use the air start cam or the lubricator eccentric. As Doug said the side shaft might have to be re timed. I'm wondering about the lube eccentric, there is quite a range of arc that the lube rod can be moved through maybe that would help setting up the timing events The part number for the Wico cam is A-361A.

Thanks for the info, Bill. The cam box on the newer engines is a little different, and the Wico adapter may not fit. They have lids on top instead of a side cover and a simple bearing retainer/seal plate where the shaft enters. It's still possible that there is a Wico adapter for them, or that I could make one and use the air start cam or put an old model box on the newer engine if I could locate one. I'm going to see if the any of the cams have the same part number as yours. I have a DP 160 twin Ajax with air start, and on it the cam box has the air start timing valves on the side and the gas injection valve on top. It has no water pump and the lubricator sits where the waterpump would be.

On your air start compression relief valve, it just needs a 3/4" line going back to the air start timing valve. Where the ell is on the head side of it, most of them have a brass drain cock. To start the engine with air, you put the sheet metal thing over the valve stem to hold it open a little and open the drain cock to let compression bleed offas you turn the engine to TDC or just a little before. Then quickly close the drain cock, pull the metal hold-down off the valve stem, and turn on the air. If you have enough air, about 90-150 psi, the engine will begin cranking and all you do then is turn on a little gas. As soon as it hits, cut off the air. It doesn't take as much volume of air to start one of these as you might think, since the air start timing valve is only open for a brief time during each revolution, maybe 50-60 degrees of rotation, and for most of that time, there is some back-pressure.

The driving bar was all worn out and elonjigated to the point I was afraid it might fail. I considered contacting one of the mag re-builders but thought I'd have a go at it my self. I am happy with the results. This should be the end of the repair part of this thread. I hope the next post to be of the freshly re-painted engine.

Well she's done at last Thanks everyone who helped with information and suggestions on how to proceed when I was at a dead end.This post would come up right after Doug's paint suggestion. I know it would have looked real classy in black with pin striping, but I had to go my own way on this part. Thanks for the info on straightening the crankshaft. And thanks Tom Weatherford.